Topic: What is your favorite iconic American structure?

From the Gateway Arch, Rockefeller Center, the Sears Tower, and the Empire State Buiding to the carvings on Mount Rushmore, the Golden Gate Bridge, the Space Needle and Mount Rushmore, the U.S. has dozens of impressive, important, and iconic structures. Which ones have you been to? Which has had the biggest impact on its local community and on the country? Which one is your favorite?